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Early human ancestors may not have passed down knowledge but simply crafted tools on instinct

Starting from a fist-size rock shaped into a tool in the early stone age, a new paper challenges the view that cultural transmission goes back for more than 2 million years.

Image credits Tero Vesalainen.

Common wisdom holds that humanity owes its success to our ability to share information. Living in today’s world, where we have almost instant access to immense volumes of information through conversation, texts, advertising, the internet, it’s easy to see why.

It’s a process anthropologists call cultural transmission, and there was a time where people simply didn’t pass information along. We don’t exactly know when the switch took place, but it’s generally believed to have happened more than 2 million years ago. Now, a team led by Claudio Tennie, Research Group Leader in the Department for Early Prehistory and Quaternary Ecology of the University of Tübingen comes to challenge that view.

Rock’a’chopper

The paper first debates the Oldowan chopper hypothesis. The term “Oldowan” is used to denote your entry-level stone-age technology. It’s represented by fist-sized rocks that are smooth on one side and had just enough material removed to make a rough edge on the other. Back in the 1960s, Louis Leaky, a prominent paleoanthropologist, attributed such an artifact to the first member of the human genus, Homo habilis, the ‘handy human’. While Leaky and his colleagues didn’t explicitly say Homo habilis learned how to produce the tools through cultural transmission of information, Premo says his usage of the word “culture” alone is enough to imply that such mechanisms were at work.

An Oldowan chopper.Image credits José-Manuel Benito Álvarez.

“All of their contemporaries figured that any stone tool must be an example of culture because they thought that humans are the only animals that make and use tools and humans rely on cultural transmission to do so,” said Luke Premo, associate professor of anthropology at Washington State University, and paper co-author.

“It made sense to them at the time that this ability might in fact distinguish our genus from all others.”

Premo and his fellow co-authors say there currently isn’t enough evidence to support a cultural transmission of the techniques used to make such tools. The team writes that it’s more likely these tools are “latent solutions” which rely on an animal’s inherent skill rather than cultural transmission — i.e. that they’re simple enough to be thought-up on the spot when needed, rather than having to be told how to manufacture them. Just like crows or chimpanzees can spontaneously learn to use tools, so too could Homo habilis have learned to make simple tools, like the Oldowan chopper, on their own.

“Our main question is: How do we know from these kinds of stone tools that this was a baton that somebody passed on?” said Premo. “Or was it just like the chimp case, where individuals could figure out how to do this on their own during the course of their lifetimes?”

The team further warns against equating complexity to a cultural flow of ideas, pointing out that while the tool looks “like it would require a lot of brain power,” animals can create very complicated structures such as beehives, beaver lodges, or spider webs, without sharing any information.

They also point out that the type of tool (rough-cut stone edges) remained virtually unchanged for over 1 million years. A culturally transmitted technique generally suffers at least slight changes over time, as individuals add on what they’ve been taught, or as information is lost. This static nature, Premo says, points to individuals with the same mental and motor skills coming up with the same solution again and again instead of the constant addition of innovations owed to information sharing today.

If it didn’t start over 2 million years ago, however, when did it start? The team points out that the production of other early hominin technologies, such as the Mousterian stone tools in use by the Neanderthals and other hominids between 160,000 to 40,000 years ago, involved many steps — as such it’s more likely that people passed it down rather than constantly re-discover the processes involved.

Overall, the authors don’t debate the fact that cultural transmission allowed us to thrive in virtually all environments around the planet.

“It does explain our success as a species,” Premo said. “But the reason we are successful might be much more recent than what many anthropologists have traditionally thought.”

If it really is such a recent feature, it could explain why we’re still having trouble coping with too much information.

“[Cultural transmission of information]can be hijacked,” Permo adds. “If you’ve got this system in which you receive information that can affect your behaviors… all it takes is somebody broadcasting information to you that makes you act in a way they prefer. And if you’re getting hundreds of messages every day, it can be difficult to discern what is important for you from what is important for somebody else.”

The paper “Early Stone Tools and Cultural Transmission: Resetting the Null Hypothesis” has been published in the journal Current Anthropology.